1. Field of the Invention
This invention relates generally to roadway markers, and is particularly concerned with roadway markers utilizing retro directive reflecting elements and to reflectors suitable for use with such roadway markers.
2. Description of the Prior Art
Roadway markers using reflectors having retro directive reflector elements have come into widespread use to dilineate traffic lanes and the edges of roadways. Such roadway markers are superior to painted strips on the roadways since under poor weather conditions, the painted strips on the roadways are not visible.
The most common type of reflector utilized in such roadway markers are those formed with cube corner reflex reflector elements. In the manufacture of reflectors having cube corner reflex reflector elements, it is common to form a die from a plurality of pins having the cube corner surfaces machined onto the ends of the pins. This is an expensive operation since a very high degree of accuracy is required. Furthermore, the reflective efficiency of cube corner reflex reflector elements decreases as the entrance angle of the light to be reflected increases with respect to the normal to the reflector surface.
Examples of prior art pavement markers, reflectors, and manufacturing methods and apparatus are disclosed in U.S. Pat. Nos. 1,906,655; 2,056,491; 2,120,524; 2,330,096; 2,360,480; 2,538,638; 2,951,419; 3,258,840; 3,332,327; 3,417,959; 3,758,191; 3,784,279 and 3,712,706.